I'm using some Thermistors with a RIO but cannot get the correct temps

All things groov RIO I"m using these, iOVEO 035HP02205 - PT1000 - Temperature probe with PVC line up to 105°C, temperature sensor.

I just cannot get them to give a correct temp reading. I have really cheap Thermistors that seem to be doing the job. When I check the resistance of the thermistor against the temp with another accurate sensor it is reading perfectly.

I just don’t know what I’m doing wrong with them?

I"m thinking I may need to bring the readings in to Node-Red and create a switch or formula to match the resistance to a node rather than using the Rio’s on board capability.

Any idea’s greatly appreciated. It feels like I’m just being bloody stupid.

Hi Jim,
welcone to the forums.

What type of Thermistor did you select in groov Manage? The iOVEO 035HPO2205 seems to have a range of -35 °C to +105 °C. You might have to select the “custom curve” type Thermistor in groov Manage and adjust the parameters accordingly.


Jim, if you get this going please let me know your results.

I have connected a PT100 to the RIO and spent quite some time trying to configure the curve to get it going. I have not had any success as the time spent doing it is not worth the squeeze.

I have had to resort to using Modbus TCP Temp modules to communicate to my RIO devices via node red where ideally I would have connected the PT100 or PT1000 directly to the unit.

Ok so we have a winner, thank you Gerhard!

Used the Steinhart-Hart Coefficients in the custom Thermistor. Obviously being an expert I simply calculated all of this in my head. Obviously that is lie.


I was lucky I had a table of resistance and temps so was able plug them in to the website above and it gave me what I needed. I’ll run some tests to see how close I am to the temps, but so far looking good!!

Cheers again.



Thanks for letting us know.